The present invention relates to liquid plant treatment compositions, e.g., fertilizers, herbicides, fungicides, insecticides, and fire retardants, and more particularly to a liquid fertilizer composition containing a dispersion of glyoxylated hydroxypropyl guar. Additionally, the present invention relates to a method of producing glyoxylated hydroxypropyl guar.
In the application of conventional liquid plant treatment compositions, including fertilizers, herbicides, fungicides, insecticides, fire retardants and the like, it is well known that optimal results are obtained by prolonged retention of the treating composition on the plant surfaces or in the soil to which applied. This is particularly true of water soluble inorganic chemical fertilizers which are known to be highly susceptible to rapid and uncontrolled leaching from the soil by surface or rain water. As a result, a significant proportion of the available plant nutrients in the fertilizer often are not absorbed and assimilated by plants growing in the soil.
A relatively significant amount of developmental work has been devoted to attempts to develop fertilizers, plant growth mediums and the like having an ability to retard the release of plant nutrients to improve the degree of nutrient assimilation by plants. Representative examples of varying compositions developed for this purpose are disclosed in U.S. Pat. Nos. 3,105,754; 3,206,297; 3,519,413; 3,649,239; 4,055,974; 4,241,537; and 4,402,725. One commonly proposed technique found in several of these patents is the use of a gelation agent in the fertilizer composition to attempt to retard nutrient leaching. One type of gelling agent utilized in several such fertilizer compositions is a natural vegetable gum such as gum arabic, gum tragacanth, gum karaya, locust bean gum, xanthan gum and guar gum, presumably chosen because of their natural hydrophilic properties and because the plants from which derived can be commercially cultivated.
Unfortunately, however, none of such fertilizer compositions are known to have become commercially accepted and successful. While the reasons for the lack of acceptance and success are not known, it is believed that difficulties may be encountered in the manufacture of such compositions due to the tendency of the gum materials utilized to resist uniform dispersion in liquid suspension, forming cakes or "gumballs". Further, it is believed that the prior fertilizer compositions produced utilizing such gum materials are not of significant effectiveness in retarding leaching of plant nutrients over any extended period of time, which may result from the susceptibility of the gelling agent to microbial degradation when applied to soil.
Another disadvantage of conventional liquid fertilizer compositions is the inability to obtain elevated concentrations of potassium as an available nutrient, commonly referred to as potash. While potassium compounds typically utilized in liquid fertilizers are soluble in water to some degree, it is typically not possible to obtain a concentration of potash in aqueous solution exceeding 9% by weight. To achieve higher potash concentrations, it is conventional to add a clay material to aqueous fertilizer solutions as a suspension agent to hold additional undissolved potash in suspension. This technique, while successful to some extent, has several disadvantages. First, under normal conditions it is still not possible to obtain concentrations of available potash exceeding 12% to 13% by weight. Further, extremely expensive specialized equipment is necessary to prepare the clay suspension and, since clays are generally abrasive in nature, the equipment becomes rapidly worn. Finally, the clay suspension, once prepared, must normally be utilized immediately since the suspension tends to settle out rapidly, within a day or less at relatively cold temperatures.
A further disadvantage of conventional fertilizers is their inability to contain both elemental calcium as a micronutrient and phosphorus-containing compounds due to the normal reactivity of calcium and available phosphorus to form the insoluble salt calcium phosphate which cannot be readily absorbed by plants as a nutrient source.
There accordingly exists a substantial need for liquid plant treatment compositions in general and liquid fertilizer compositions in particular having an ability to resist washing and leaching of the constituent plant treatment chemicals, nutrients and the like. There further exists a need for liquid fertilizer compositions wherein relatively high concentrations of potash may be obtained easily and inexpensively and wherein both elemental calcium and phosphate compounds are held unreacted with one another to be readily available for plant absorption and assimilation.